DIY vacuum cleaner filter???

[T42]

In my workshop I have a 30-year-old Friom drum vacuum cleaner  whose filters are like big paper bags that simply fasten round the motor block with a long spring with a hook at each end, like a bungee cord. The last of these just ripped. No harm to it, it's been in service for around 25 years.

The company no longer exists, unless it's an inscrutable bunch that Google turned up in Hungary but me no spikka da lingo.

Any idea what kind of material I could cobble together a filter out of?  I don't really want to fork out for a new vacuum.

[mrcharly-YHT]

A lot of them are generic. What are the dimensions?

[T42]

About 15cm (6") in diameter and 25 cm (10") long, completely open at the top like an old paper grocery bag.

Just patched it from the inside with duc[k,t] tape. Discovered in doing so that the "long spring with a hook at each end" is in fact a length of twine, a big rubber band and a wire hook.  We'll see what happens.  I'll try it outside first: yesterday the workshop looked to be full of smog when I looked up from the sander.

[mrcharly-YHT]

I remember that type and fastening, I'm sure I've either owned a hoover that was like that.

There are thousands of bags for sale on ebay if you search for 'vacuum cleaner bag', you can flick through the listings. Or try making a bag up from a double thickness of tyvek.

[JonBuoy]

Tyvek isn't particularly porous.

[mrcharly-YHT]

In comes in quite a few grades - and is used in filters.

The brown paper used for vacuum cleaner bags isn't all that porous, you do want the bags to trap fine dust.

[T42]

<coff><hack><coff> You're right there.

My jury-rigged bag works, but with a belt sander dust extraction is little more than a pious hope.  It works on other machines, though. Sort of.

Anyway, I'll have a poke round the bay. All the bags I've seen so far, though, have wee cardboard holes at the top.

Tyvek, huh??? I'll try that.

Cheers 

[Jurek]

This site over-simplifies things IMHO.
I did some work with Electrolux (on vacuum cleaners, funnily enough) when I was studying for my degree in industrial design. It transpires that two key things affect the effectiveness of vacuum cleaners, and neither is the size / wattage of the motor.
One is the stainless steel plate underneath the 'brush' end of the cleaner. The grooves in these plates, and the radii on their edges are (down to .01mm) critical in how effectively the cleaner operates. There are (or were) only a couple of manufacturers worldwide, producing these plates and supplying them to vac cleaner manufacturers.
The second, and more relevant to your use (which I see as more extractor / less vac cleaner) is the weave of the material used for the bag. Once again, this is a highly specialised / dark art, the knowledge of which lies with a handful of companies worldwide, who produce the material for vac bags to sell on to vac cleaner manufacturers, in addition to (perhaps unsurprisingly) producing material suitable for the manufacture of tea bags - it's all about filtration - innit - and I suspect that people who have invested heavily in finding out what works and what doesn't, aren't likely to give up that information readily. Hence, it might not be so easy to acquire the material you need.

I'm interested to hear how you get on.
G'luck.

J

[The French Tandem]

My prefered material for making DIY vacuum filters is geotextile fabric, the kind that you can find in the gardening department of your local DIY store. It can be either sewed, or welded with a propane torch.

My jury-rigged bag works, but with a belt sander dust extraction is little more than a pious hope. 

In my shop, all the machines are ducted to the same big dust extractor, except for the belt sander who has its own extractor. The main extractor recycles its air into the shop, but the smaller extractor for the sander rejects its air flow outdoor.

[Neil C]

I have an H1 bag from an old upright Hoover - the type that is just a simple bag and is held on a tube with a rubber band.

It measures 52 cm circumference ( which is about 6 1/2 inch diameter ) and 45 cm long.

That should fit your stated size.

[andytheflyer]

My prefered material for making DIY vacuum filters is geotextile fabric, the kind that you can find in the gardening department of your local DIY store. It can be either sewed, or welded with a propane torch.

In principle the use of a geotextile is on the right track.  But (isn't there always...) geotextiles like the non-wovens sold in the DIY stores are designed to provide a separation and a filtration function when used in (my old profession of) ground engineering.  I used to specify the geotextile needed to filter out groundwater, or to keep two materials apart, predicated upon the grain size distribution of the soil that was to be separated from an overvening (usually granular layer such as a road base or drainage medium).  The criterion is the apparent opening size of the geotextile - being the size at which a percentage (usually 90%) of the soil stays on one side of the geotextile.

So, if you were to use a DIY store geotextile it will have been selected (I'd hope) to keep soil on one side, and someone will have assumed a grain size distribution for that soil.  If you want to filter workshop dust, I'd venture to suggest that the dust particle sizes will be a lot smaller than the typical soil assumed by the DIY store (going by my experience when woodworking!). That would mean that too much dust will pass through a bag made of that geotextile.

If you were able to determine the particle size distribution of the dust, you may well be able to find a geotextile with a fine enough apparent opening size to filter 90% of the dust out of the airstream. 

So, a geotextile could be a good idea, but it would need to be selected on the basis of its apparent opening size and the particle size distribution of the dust to be filtered out of the airstream and retained in the bag, in order to be sure of it being suitably effective.  Perfectly do-able, but needs a bit of science and design.  The calculation method is on the internet.

[The French Tandem]

So, a geotextile could be a good idea, but it would need to be selected on the basis of its apparent opening size and the particle size distribution of the dust to be filtered out of the airstream and retained in the bag, in order to be sure of it being suitably effective.  Perfectly do-able, but needs a bit of science and design.  The calculation method is on the internet.

Well,  what you said makes a lot of sense, but collecting dust from a belt sander is really a pain in the a***. If your filter is fine enough to collect the finest particles, it will get clogged within a few seconds of normal use. If your filter has larger openings, it won't get clogged, but all the fine particles will end up in your lungs. That's the reason why I use a separate dust extractor for the belt sander, and direct its air flow out of the shop.

[andytheflyer]

Which is why James Dyson went for the cyclone.  Bags have to be a compromise in that their filtration function can only be effective if the dust particle size matches the apparent opening size of the filter material, and in real life it probably never does!

[Vince]

I have an old Aquavac Bulldog which had a similar bag filter. The bags were replaced with a drum that has a closed end. Might this be a suitable replacement?
https://www.amazon.co.uk/Spares2go-Filter-Cartridge-Aquavac-Cleaners/dp/B00S6K4DI6/ref=sr_1_8?ie=UTF8&qid=1498859426&sr=8-8&keywords=aquavac+bulldog

[T42]

Thanks, everybody. 

Looks like I can do several things (well, I've already done one of them):

- buy a Triton (or equivalent) dust collector and use the unfiltered vacuum cleaner as a suction device only.  Drawback: at present my vacuum has two different hose diameters that fit several devices. The Triton just has one.

- try Vince's Aquavac-style filters (promising).

- try the H1 bag (ditto)

- experiment with various geotextiles / Tyvek.  Looks like a more specialized subject that I thought (mainly because I hadn't thought about it that much).  Time-consuming: I'm rebuilding a bass to a deadline & it's not going that well.

- put the sanders on a mobile bench and sand outside. This I have done. Drawbacks: (a) rain and (b) neighbours.  OTOH we didn't complain when they built their miniature Taj Mahal. And (c) wheeling the thing outside for every piddling joblet is a pain.

In the meantime the duc[k,t] tape is holding up.

[CarlF]

I've got an Earlex (rebadged as Wickes) wet and dry vac that originally came with the paper bag type filter, about that size. There's a better pleated filter upgrade that I've fitted (like Vince's linked aquavac one) so I don't have the paper one around any more to check the size. But Earlex sold that model for ages, and I think they sold tons of them, so that might be an easy to find alternative possibility.

There's loads of places online selling generic spares and accessories for vacuum cleaners though, I'm sure you should be able to find a close match.

Is the Triton dust collector the fairly simple bucket with two holes in the lid that goes between the tool and the vacuum? If so, I don't think it's much good for dust, it's more for something like a planer that produces large quantities of chippings that would quickly fill the vacuum cleaner. An actual cyclone, however, does a good job. I am pleased with the one I made up using a "Dust Commander" knock-off of the over-priced "Dust Deputy"(one of these: https://www.amazon.co.uk/DUST-COMMANDER-DLX-performance-collector/dp/B00JR3NQAC/ref=sr_1_4?s=diy&ie=UTF8&qid=1498912170&sr=1-4&keywords=cyclone+dust+collector) and it looks like there are a few even cheaper options now. Getting the hoses matched up is a faff though, but that's an issue anyway unless you've gone all Festool or something and matched all the tools and the extractor from one brand.

[T42]

Nah, my power tools are a mongrel bunch going back to the days when ciggies knew no filters and dust didn't bother *real* men.

The Triton doodah looks like a plastic bucket with hoses, though they do describe it as a dust collector. The Dust Commander looks better, though, esp. as it looks adaptable to several different hose diameters.  And there are various hose purveyors, whereof dirt-cheap-dirt Einhell. Looks like a good way to go.

I might wait a month, though, and get a proper double-bag extractor.

I used to drive past the Festool factory in Wendlingen every day.  There was a gasthaus there that offered Bavarian camembert deep-fried in beer batter, served in the usual way with cranberry jelly. Impressive.

[T42]

Poking about on YouTube I found a bunch of videos about DIY cyclones made out of plastic buckets & pipes.

[CarlF]

Oops... sorry if you've fallen down the DIY cyclone rabbit hole. You'll have run across Bill Pentz theorising about the perfect setup by now, I assume. I didn't have the patience for all that fabrication and experimentation. Making a clamp on lid for a suitable bin, mounting the pre-made cyclone on it, and assembling it onto a cart that carries the vacuum and all its hoses etc. was plenty of effort. Especially with the aforementioned faff of getting various hoses matched up.

[Wanlock Dod]

not sure if this might be the kind of thing you were after:
http://www.dm-tools.co.uk/product.php/section/5743/sn/RPWDX1500E#.WWNrDoTyuUk

[T42]

In the end (almost) I didn't go the cyclone route, simply because finding a bucket with a clamp-on lid proved impossible in our area. "It's because people use disposable nappies these days" says the missus. Quite.  Resorting to the internet to buy a plastic bucket seemed ridiculous.

I did see a few on the internet, though.  "With inviolability seal. Partly in stock" says one offer.  Later, maybe.

not sure if this might be the kind of thing you were after:
http://www.dm-tools.co.uk/product.php/section/5743/sn/RPWDX1500E#.WWNrDoTyuUk

I have received a bunch of Hoover bags and will presently be cobbling a Frankenbag together.

[Brucey]

if you are frankenbagging or in the mood for experimentation, there is another textile that is worth looking at; this is a non-woven felt that is meant for use beneath flat roofing materials. I use pieces of this material as secondary filters in

- IC engine air filters
- cyclone vacuum cleaners

Filtration is a funny business; most primary filters rely to some extent on the presence of already-trapped material to provide some of the filtration effect.

Nearly all filters (physical and cyclone type) don't filter 100% efficiently, but are statistical sorting devices, whereby entrapment rates vary with particle size and weight.

You can demonstrate this quite nicely by replacing the secondary filters from a cyclone cleaner, then attempting to 'vacuum clean' the old filters. Typically none of the crud is caught in the cyclone. Most of it ends up on the new filters, but some of it passes right through.

cheers